In 1946 the War Assets Administration (WAA) returned the airport to the County. In 1947 the transfer was formalized and the airport was named for County Supervisor William J. Buchanan, who served on the County Board of Supervisors for more than forty years. The airport continued to be used on occasion by the U.S. Army to transport troops, especially during the Korean War.[5]

Beginning in the 1990s the Board of Supervisors updated the Buchanan Field Airport Master Plan. Commercial development of adjacent property such as Sam's Club, Taco Bell, Sports Authority, and Jiffy Lube was allowed in 1992.[5] The future direction of this airport is always in question because of its location on prime property in the middle of the city of Concord with no room to grow, and noise concerns. The County has developed a new airport in Byron in the eastern part of the county.[5][6]

For decades, it was common for jets to fly over residential areas. In recent years, complaints have restricted planes flying over such areas to personal aircraft using propellers.

Commuter airline flights to San Francisco International Airport (SFO) with small prop aircraft started in 1969, but were gone by 1980. One commuter airline was Stol Air Commuter flying Britten-Norman Islanders. Pacific Southwest Airlines (PSA) began flights from Buchanan Field to Los Angeles International Airport on May 1, 1986. PSA had four to five daily roundtrips with BAe 146-200s, initially with 100 seats. USAir continued the flights after acquiring PSA in 1987, but replaced the BAe 146s with de Havilland Canada DHC-8 Dash 8 turboprops in 1991. That year USAir announced that it was dismantling most of the West Coast network that it had acquired from PSA, including Concord, where flights ended in 1992. Buchanan Field has not had scheduled passenger flights since. WestAir operated deHavilland Twin Otters (and perhaps Short Bros types) into CCR from Sacramento, Stockton, and San Francisco in the years either side of 1985 or so. They were discontinued before WestAir became a full United Express carrier.

On the evening of December 23, 1985 a Beechcraft Baron N1494G, executing a missed instrument approach procedure from an approach to runway 19R, lost control and crashed into the roof of the Macy's Department Store at nearby Sunvalley Mall, killing the pilot and two passengers and seriously injuring 84 Christmas shoppers in the crowded mall, mainly by spraying them with burning fuel. Four of the victims on the ground later died. The accident brought increased opposition to the airport and caused Pacific Southwest Airlines to delay scheduled passenger flights that had been planned to start in January 1986.

Another plane crashed on April 13, 2004, shortly after leaving Buchanan Field. The plane landed on a minivan traveling down nearby Interstate 680 in Pleasant Hill and nearly severed the left leg of a 12-year-old girl (Her leg was successfully reattached and she has made a near full recovery). Officials determined the crash was the fault of a mechanic who had worked on the plane.[7]

On December 21, 2006, at about 1900 Zulu, a Piper Malibu (PA46) crashed while flying the LDA (Localizer Directional Aid) approach into CCR. The aircraft was flying too low and hit obstructions on the ground. The plane hit the median of Highway 4, crashing between the highway and Marsh Drive just north of the runway. Three passengers were killed instantly one died after surgery.[8]